Prior art assemblies used for feeding multiple parts such as screws or bolts to an assembling machine have several inherent problems. The assembly generally consists of a gravity feed or similar mechanism for delivering parts to a track feed or platform having a plurality of openings therein. The assembly must be timed so that an opening is disposed below the feed line for a part to fall into the opening and then the track feed is advanced to dispose the next opening below the feed line to receive the next part. The track feed, or escapement, may include a plurality of openings in it to sequentially receive parts which are fed to an assembling mechanism. Prior art actuating mechanisms require a slow speed to accomplish this meticulous operation. Prior art mechanisms have been driven by a hydraulic mechanism. These mechanisms developed leaks and were inefficient. They lacked the ability to actuate the precise movement required for the operation. Additionally, prior art mechanisms have been found to be energy inefficient and quite noisy.
Drive mechanisms including stepping motors for driving a ball screw to advance linearly in a step fashion have been adapted to various arts. The U.S. patent to Nickels et al 4,089,624, issued May 16, 1978 discloses a pump assembly including a motor assembly which is a pulse operated stepping motor. A pump piston is mounted for movement in an axial direction into and out of a pump cylinder, the piston being secured to a lead screw. A timing belt provides a driving connection between the motor and drive shaft. The upper end of the drive shaft axel includes a driven nut which upon actuation of rotation by the motor linearly extends and retracts the screw and piston.
The U.S. Pat. Nos. to Price et al 3,793,896, issued Feb. 26, 1974, and to Lawler 3,803,927, issued Apr. 16, 1974 disclose incremental linear positioning apparatus. The apparatus include a stepping motor for driving a ball nut assembly. These assemblies have been used for positioning in very small increments a workpiece or machine element.
This invention relates to the art of feeding parts to an assembling machine and provides energy efficiency and noise reduction with a concommitent increase in speed of operation. The elimination of hydraulic or pneumatic piping and valving provides an associated elimination of fluid leakage. The result is a cost effective function.